Portugal was among the euro zone countries hardest hit by the global financial crash of 2008. It was forced to request an international bailout from the European Union (EU) and International Monetary Fund (IMF) in 2011, and has since undergone tough spending cuts and reforms.

The move, which means Portugal will no longer have to answer to its bailout lenders -- the International Monetary Fund and fellow euro zone countries -- has led to some concerns that the country could relax its efforts to turn around it economy, especially given a general election in a year's time.

But Passos Coelho, who is leader of Portugal's Social Democratic Party, insisted there was no risk of this given that the Portuguese public understood that reforms needed to continue.

"We will maintain the fiscal responsibility, the necessary support to maintain financial stability and we will boost the reform momentum," he said.

An asset-purchase, or quantitative-easing (QE), program would be something of a drastic change in policy - and is not something supported by Passos Coelho.

"No one in the ECB can tell we ever conceived a situation where a policy like this could be adopted, but it's not the mission of the ECB to improve the economic recovery," he said.

Instead, Passos Coelho said he would prefer the central bank to play a less active role in Europe's economy. "It's important that the European economy can recover by its own possibilities," he said.

His comments come after the ECB opted to keep monetary policy unchanged last week. However hints by Mario Draghi, the president of the central bank, have led many to expect some stimulus measures – although perhaps nothing as drastic as QE – to be unveiled at the ECB's June meeting.